JP2008501536A - Method and apparatus for controlling machining of machine parts - Google Patents

Abstract

A method and a relevant apparatus for controlling the machining of a piece ( 18,38 ) rotating in a numerical control machine tool ( 33 ) includes the steps of detecting instantaneous values (V(i)) indicative of the dimensions of the piece during the machining, performing dynamic processing of the detected instantaneous values and controlling at least one machining phase on the basis of the processing. The method includes dynamic calculation of average values (M(j)) of sequences of the detected values, acquisition of a variation index (P) indicative of the average values trend during the machining and of a correction coefficient (K) that allows for the delay of the calculated average values with respect to the actual dimensions of the piece, and processing of an instantaneous dimension (RI) of the piece that is transmitted to the numerical control of the machine tool for controlling the machining.

Description

  The present invention relates to a method for controlling the machining of rotating parts in a machine tool by means of an inspection device. The method includes a step of detecting an instantaneous value indicating a radial dimension of a part, a step of calculating the detected instantaneous value, and at least one machining step based on the detected and calculated instantaneous value. And controlling the process.

  The invention further relates to an apparatus for inspecting rotating parts during machining of a numerically controlled machine tool. This apparatus cooperates with a rotating part and sends an electrical signal indicating the dimensions of the part, and an arithmetic processing unit connected to the inspection head and a numerical control device of a machine tool- Display device. Arithmetic processing—The display device receives signals from the inspection head, inspects and computes instantaneous values, and performs numerical control on signals indicating the dimensions of the parts.

  It is known to machine machine parts, more particularly with numerically controlled grinding machines, while inspecting them during the manufacturing process. In-process inspection detects part dimensions during machining and indicates that preset dimensions have been reached in order to control machining stoppage and / or subsequent transition to machining process This is done by using a measuring head or other inspection and / or measuring device that sends a signal.

  EP-A-0791873 discloses a specific machining method in a grinding machine. According to this method, the machined part is a crankpin of the crankshaft and orbits about the main axis of the shaft. At this time, the grinding wheel slide translates with respect to the main axis.

  In machining this type of part, it is difficult to reach the very high accuracy standards currently required. This is because it is now necessary to shorten the manufacturing time. In fact, the machining cycle must be very short, and the ratio between the grinding wheel machining feed rate (which determines the material removal rate) moving towards the pins and the rotational speed of the shaft is large. Therefore, the cross-section of the pin undergoing machining deteriorates in axial symmetry from moment to moment and up to the final step, for example, the “sparkout” step, ie the radial dimension depends on the required accuracy. From one point to the other. For this reason, one or more pins that contact only a specific surface area of the pin (this surface area is necessarily away from the area that is actually being machined at the moment the machining is performed) Inspection during the manufacturing process carried out by known heads with contacts is particularly difficult. The machining method according to EP-A-0791873 referred to in the above description follows when the grinding wheel slide is being machined towards the pin (following the orbitally rotating pin without removing material). Therefore, when the inspection head sends a signal during the manufacturing process that indicates that the preset diameter dimension has been exceeded by a specific cutting allowance greater than the desired final dimension, when the slide continues to displace) A series of processes including a process of stopping at an intermediate position is assumed. In this method, when the grinding wheel slide is at an intermediate position, the average value is calculated by calculating the dimension detected by one or more rotations of the pin, and the desired dimension is calculated from the average value. It is assumed that the subsequent grinding wheel slide feed amount necessary for reaching the above is determined. Retract the inspection head in the last part of machining and deactivate it. This assumes that the grinding wheel slide is machined by a predetermined amount and the final “spark out” process is performed. At this time, the grinding wheel slide is stopped again.

  The method according to the European patent application mentioned above seeks to solve the problems caused by the much higher requirements regarding the production speed and the resulting accuracy.

  However, the proposed machining cycle was burdened with control and additional work to interrupt and continue machining feed of the grinding wheel slide before reaching the desired dimensions. This is incompatible with the need to reduce machining time. In addition, such additional work leads to degradation of related electrical and mechanical parts, causing failure of the grinder and reduced performance.

  An apparatus for performing an in-process inspection of a crankpin in orbit is described in International Patent Application No. WO-A-9712724 filed by the applicant of the present application. This device consists essentially of a V-shaped reference element that rests at two points on the surface of the pin to be inspected, and a line that contacts the surface of the pin between the two resting points and bisects "V". And an inspection head having a movable contact for transmitting the displacement along a predetermined direction corresponding to the above to the transducer means.

  The device manufactured by the owner of this patent application in accordance with the teachings of International Patent Application No. WO-A-9712724 ensures excellent results from a metallurgical point of view, is most easily applied and has an inertial force. The performance standard achieved with the grinding machine in the related application is small and confirms that the quality and reliability of the adopted solution is excellent.

  However, the disadvantages mentioned above are also present in these devices due to the requirement to increase the machining speed without changing or improving accuracy.

  It is an object of the present invention to provide a method and associated apparatus for controlling the machining of machine parts that can be machined with considerable accuracy and reliability in a very short time.

  These and other objects are achieved by the method according to claim 1 and the apparatus according to claim 12.

  The method and apparatus according to the invention are advantageously used for controlling operations for grinding a pin in orbit.

  One of the advantages provided by the method and apparatus according to the present invention is that it can efficiently compensate for errors that may occur, for example, by using an apparatus with a “V” shape reference element.

  The invention will now be described with reference to the accompanying drawings, given by way of non-limiting examples, illustrating preferred embodiments of the invention.

  FIG. 1 shows an apparatus according to the invention for controlling the machining of a part in a machine tool, and more particularly a grinding machine equipped with a computer numerical controller (CNC) 33 in a crankpin 18 of a crankshaft 34. Fig. 2 shows a device in production process for inspecting The crankpin 18 is substantially cylindrical and defines a symmetry axis 2. The main journal 38 of the crankshaft 34 can be inspected with the same device. Many structural features of this device correspond to the structural features shown and described in International Patent Application No. WO-A-9712724 referred to above.

  In the embodiment shown in FIG. 1, the grinding wheel 4 is connected to the grinding wheel slide 1. The slide 1 defines a rotational axis 3 for the grinding wheel 4. A work table 23 supports a crankshaft 34 and defines a rotation axis 8 of the crankshaft 34. The grinding wheel slide 1 supports a support device that includes a support element 5, a first rotary connecting element 9, and a second rotary connecting element 12. The support element 5 supports the first rotary connecting element 9 by a rotation pin 6 that defines a first rotation axis 7 parallel to the rotation axis 3 of the grinding wheel 4 and the rotation axis 8 of the crankshaft 34. The connecting element 9 supports the second rotating connecting element 12 by a rotating pin 10 that defines a second rotating axis 11 parallel to the rotating axis 3 of the grinding wheel 4 and the rotating axis 8 of the crankshaft 34. A tubular guide casing 15 is coupled to the free end of the coupling element 12. In the guide casing 15, the transmission rod 16 which supports the contact 17 for contacting the surface of the pin 18 to be inspected can be translated in the axial direction. The tubular casing 15, the rod 16, and the contact 17 are parts of a measurement head, that is, an inspection head 39. The inspection head 39 further includes a support block 19 fixed to the lower end of the tubular guide casing 15. This block 19 supports a V-shaped reference device 20 adapted to engage the surface of the pin 18 to be inspected by the rotation allowed by the rotating pins 6 and 10. The transmission rod 16 can move substantially along a line that bisects the V-shape of the reference device 20, or it can move according to a predetermined direction that is slightly angled with respect to the bisector.

  The support block 19 further supports the guide device 21. This guide device guides the reference device 20 and engages the pin to be inspected, as described in the above-referenced international patent application WO-A-9712724, so that the reference device 20 is removed from the pin. Helps maintain contact with the pin as it moves away. This is to limit the rotation of the first connecting element 9 and the second connecting element 12 about the rotation axes 7 and 11 defined by the pins 6 and 10.

  The axial displacement of the transmission rod 16 with respect to the reference position is detected by a measurement transducer fixed to the casing 15. The transducer is, for example, a transducer 41 of the LVDT type or HBT type (known per se and not described in detail here), a fixed winding, and a ferromagnetic core that can move with the transmission rod 16. It has.

  The transducer 41 of the head 39 is connected to the arithmetic processing / display device 22, and this device is connected to the numerical control device 33 of the grinding machine.

  The crankshaft 34 to be inspected is positioned on the worktable 23 between the spindle and the tailstock (not shown). The spindle and tailstock define a rotational axis 8 that coincides with the geometric main axis of the crankshaft 34. The crankpin 18 and the main journal 38 rotate about the axis 8. The crankpin 18 passes through a predetermined track path.

  The actuator device includes a hydraulic double-acting cylinder 28, for example. The cylinder 28 is supported by the grinding wheel slide 1 and includes a rod 29 connected to the piston of the cylinder. A cap 30 is provided at the free end of the rod. An arm 14 is connected to one end of the element 9, and this arm supports an abutting body including an idle wheel 26 at the opposite end. Actuating the cylinder 28 and displacing the piston and rod 29 to the right (relative to FIG. 1) causes the cap 30 to contact the abutment 26 and displace the inspection device to the rest position, so that the reference device 20 is Move away from the surface of the pin. An overhang 13 is firmly fixed to the support element 5, and a coil return spring 27 is connected to the overhang 13 and the arm 14. In order to be able to displace the device to the inspection state, when the rod 29 is retracted and the cap 30 is moved away from the abutment or idle wheel 26, the support block 19 is rotated by the rotation of the connecting elements 9, 12 so that the crankpin 18 Approaching (or main journal 38), the device reaches the inspection state and maintains this state. This is done substantially in the manner described in the international patent application WO-A-9712724 mentioned above. This is referred to for further details. The cooperation between the crankpin 18 or main journal 38 and the reference device 20 is maintained by gravity. The action of the coil spring 27 is particularly important in the inspection of the crank pin 18 that performs the orbital motion shown in FIG. In fact, the tension of the spring 27 increases as the support block 19 is lowered, and partially and dynamically cancels out the forces due to the inertia of the moving components of the inspection device by following the displacement of the crankpin 18. In this way, for example, in the lower position (indicated by reference numeral 18 ″), it is possible to prevent excessive stress from being applied between the reference device 20 and the crankpin 18. If an excessive stress is applied between the reference device 20 and the crankpin 18, the V shape of the reference device 20 is deformed. On the other hand, during the upward movement of the device (due to the rotation of the crankpin toward the upper position 18 ′), the pulling action of the spring 27 is reduced, so that the V-shaped reference device 20 and the crankpin 18 are removed from the engaged state. Thus, the inertial force at the upper position 18 ′ can be appropriately offset. It should be understood that in this latter case, a counteracting action is obtained by reducing the pulling action of the spring 27. In other words, the coil return spring 27 does not generate any pressure between the reference device 20 and the crankpin 18, and the reference device 20 and the crankpin 18 cooperate with each other only by gravity.

  The transducer 41 of the head 39 sends a signal to the arithmetic processing / display device 22. The values of these signals indicate the position of the transmission rod 16 and thus the position of the contact 17. In such a device 22 including the memory unit 24, the signal arriving from the head 39 is processed as described below with reference to FIGS. 2, 3, and 4. FIG.

  FIG. 2 shows the contact 17 of the head 39, the transmission rod 16, and the V-shaped reference device 20 in a simple form during the manufacturing process inspection process of the crankpin 18. This process is also shown in FIG. 1, which shows the grinding wheel 4 grinding the outer surface of the crankpin 18. The pin 18 rotates in an orbital motion about the axis 8 of the shaft 34 and thus about the axis 2 in the direction indicated by the arrow A. In this process, the grinding wheel slide 1 receives the control from the numerical control device 33, and therefore follows the orbital movement displacement of the pin 18 so as to translate along the direction X with respect to the axis 8, and the material from the surface of the pin 18 Additional machining feed is made along the direction X with respect to the axis 2 of the pin 18. Many types of machine tools can envisage displacing the work table 23 in order to implement the follow-up displacement and / or machining displacement referred to above.

  Two circular lines 18I and 18F schematically outline the outer surface of the pin 18 at the instant I. These contours are respectively the final contours of the surface that can be obtained by stopping the machining feed of the grinding wheel slide 1 at the same instant I. In FIG. 2, a helical profile 18I, determined by the ratio between the machining feed rate of the slide 1 and the rotational speed of the pin 18, is deliberately exaggerated with respect to the actual size for illustrative purposes. It should be understood that there is.

  In the cross section of FIG. 2, reference symbols W and G are attached to points on the surface of the pin 18 that contact the grinding wheel 4 and the contact 17 at every moment. W and G indicate a machining area and an inspection area, respectively. The displacement direction of the rod 16 including the point G is substantially directed toward the axis 2 of the pin 18, and forms an angle α with respect to a straight line toward the axis 2 of the pin 18 including the contact point W with the grinding wheel 4.

  The inspection area can be indicated by point G, but it should be understood from a conceptual point of view that the machining area has a predetermined length in a direction perpendicular to the plane of FIGS. . However, in this description, only the contact point W between the pin 18 and the grinding wheel 4 in the illustrated cross section is referred to for the sake of simplicity and clarity.

  The signal sent by the head 39 during rotation of the pin 18 and detected at a predetermined frequency by the device 22 forms a series of instantaneous values V (i) proportional to the radial dimension of the pin 18. As shown in FIG. 2, at an arbitrary moment I, the radial dimension of the pin 18 at the contact point W with the grinding wheel 4 is different from the dimension detected by the head 39 at the point G. Thus, each detected instantaneous value V (i) represents the machining dimension actually reached at point W after a predetermined delay.

ここで、ｓは、最も新しく検出された瞬間値Ｖ（ｉ）を示す漸増数であり、Ｎは、シャフト３４が軸線８を中心として完全に一回転するときに検出され、ユニット２４に記憶された瞬間値Ｖ（ｉ）の数である。 By the first calculation process performed by the device 22, the average value M (j) given by the following expression 1 can be dynamically calculated.

Here, s is an incremental number indicating the most recently detected instantaneous value V (i), and N is detected when the shaft 34 makes a complete revolution about the axis 8 and is stored in the unit 24. The number of instantaneous values V (i).

  Due to the average value M (j), i.e. the instantaneous rolling average value, the V-shaped device 20 which is particularly susceptible to the shape error of the pin 18 which causes an undesired displacement of the contact 17 contacts the surface of the pin 18. It is possible to compensate for the change in the detected value V (i) introduced by doing. The rolling average value M (j) is continuously updated in accordance with all the latest instantaneous values V (i) in the series of instantaneous values. The average value M (j) of the instantaneous value V (i) detected in the previous revolution at the instant I is also “delayed” with respect to the dimension being machined at point W. FIG. 2 shows the radial position of the average value M (j) at the instant I, and the broken line 18I ′ shows the contour part which is the basis for the calculation of the average value M (j).

  The method according to the invention for controlling pin machining using the apparatus shown in FIGS. 1 and 2 is described below with reference to the block diagram of FIG. 3 and the graph of FIG.

The diagram block of FIG. 3 has the following functions.
Block 50-Start of control procedure.
Block 51-Position the head 39 in the inspection position on the orbiting pin 18. At this time, the grinding wheel slide 1 is performing displacement along the direction X. This includes a machining feed towards the pin 18.
Block 52-Get data and initialize control variables.
Block 53—Control of the numerical controller 33 verifies the start of the inspection process during the manufacturing process.
Block 54—Acquire and store the instantaneous value V (i) based on the signal transmitted from the head 39.
Block 55-Verify that the first scan over 360 ° performed by contact 17 on the surface of pin 18 has been completed.
Block 56-Increase the number of the acquired instantaneous value V (i).
Block 57-Dynamically calculate and store the average value M (j) of the series of instantaneous values V (i) acquired in the most recent 360 ° scan.
Block 58—Compare between the number of stored average values M (j) and a predetermined set number.
Block 59-Obtain the change index P indicating the trend of the number C of the most recently acquired and stored average value M (j), more specifically dynamically calculated and stored.
An instantaneous dimension _{R I} of the block 60 - pin 18 dynamically calculated.
It performs a comparison between the block 61- calculated instantaneous dimension R _I instantaneous dimension blocked 62- calculates and transmits to the grinding machine numerical control device 33 to R _I with the desired nominal dimension R _F.
Block 63—Control to stop machining feed of grinding wheel slide 1.
Block 64-Delete the oldest average value M (j) stored in unit 24.
Block 65—Verify that the inspection process during the manufacturing process is completed when the numerical controller 33 is controlled.
Block 66—End of control procedure.

The graph of FIG. 4 shows curves V, M, and R. These curves, the detected instantaneous values V (i), the average value M (j), and it shows a tendency in temporal order each of the calculated instantaneous radial dimension R _I.

The method according to the diagram of FIG. 3 involves the physical positioning of the head 39 on a pin 18 to be machined with a grinding machine (block 51) and simultaneously obtaining and setting several parameters (block 52). Is assumed. These parameters include the part rotation speed ω, which is a machining parameter of the grinding machine, the angle α indicating the point G at which the contact 17 contacts the surface of the pin 18, the sampling period T of the instantaneous value V (i), and, for example, A number C that determines the number of average values M (j) set by the operator is included. These parameters must be held simultaneously in the memory unit 24 for proper processing, as will be described in more detail below. The number N mentioned above of the instantaneous value V (i) detected for every complete revolution of the pin is expressed in terms of the part rotational speed ω (eg expressed in rpm) and the sampling period T (eg expressed in seconds). It should be understood that from the parameters with respect to) can be obtained as shown in equation 2 below.

When the numerical controller 33 of the grinding machine sends a signal for starting an inspection cycle during the manufacturing process (block 53), a process of acquiring and storing a sample of the instantaneous value V (i) is started (block 54). 56). When it is detected that a scan over 360 ° has been completed, for example by checking that the Nth instantaneous value V (i) has been acquired (block 55), the first average value M (j) is Dynamically calculated by 1 (block 57) and stored in unit 24. The step of obtaining the instantaneous value V (i) (block 54) and the subsequent step of calculating the average value M (j) (block 57) comprise the average value M ( It continues until the number j) matches the set number C (block 58). Thus, using such an average value M (j), the value of the change index P is calculated according to Equation 3 below (block 59). The value of the change index P indicates the slope of a curve indicating the tendency of the average value M (j) in time in FIG.

  The index P is a negative number indicating an average change in the average value M (j) between one sample and another sample based on an average value of a predetermined number C.

ここで、

である。 Current average value M (j), on the basis of the variation index P, and the correction coefficient K, dynamically calculating instantaneous radial dimension R _I by Equation 4 below. The correction factor K is a factor that takes into account the evaluation delay introduced by the configuration of the system, more specifically by the mutual arrangement of the points G and W.

here,

It is.

  In practice, K is the machining point W at the same instant I as the number N mentioned above and the average value M (j) of the instantaneous value V (i) detected for every complete revolution of the pin. This is a correction factor that takes into account the delay between the dimensions reached.

Referring to the graph of FIG. 4, at the moment I,
The value V (i) is detected,
-I = (s- (N-1)),... Detected in the last 360 ° rotation. . . , Calculate an average value M (j) based on N instantaneous values V (i) for s, and store it,
-J = (s- (C-1)),. . . , Based on the last C average values M (j) for s, an index P indicating the slope of the curve M is evaluated,
- calculating the instantaneous radial dimension R _I.

An evaluation of the radial dimension is the dimension R _I arithmetic processing pin 18 of the W point where machining of the pin surface is performed - to transfer from the display device 22 to the numerical controller 33 of the grinding machine (block 61). The numerical controller 33 advantageously verifies this when the instantaneous radial dimension R _I reaches the value of the desired nominal dimension R _F (block 62) and thus machining the grinding wheel slide 1. The stopping of the feed is controlled (block 63). Administration of the instantaneous radial dimension R _I provided by the apparatus 22 will, in any event, as mentioned hereinabove, operation described with reference to block 62 and 63, and / or other possible machining It should be understood that the displacement is determined by the numerical controller 33 of the grinding machine which controls the displacement based on a suitable program. The program depends, inter alia, on the characteristics of the part that is to be machined. The end of the inspection during the manufacturing process (block 66) is also confirmed immediately after the machining feed of the grinding wheel 4 is stopped or, for example, immediately thereafter by the control of the numerical controller 33 (block 65). Block 64 of FIG. 3 shows in a simplified form an update of the stored average value to keep only the last C calculated average values M (j) in the memory unit 24. This update is performed, for example, by deleting the oldest value M (j) for j = (s− (C−1)) among the values used for calculating the index P. This is done to replace this oldest value with a new value in a subsequent operation (block 57) after the update.

In the graph of FIG. 4, the instantaneous I _F indicates the moment at which the dimension R _I obtained by the calculation reaches the value R _F. According to the example described above, the numerical control device 33 controls the stop of the machining feed in the direction X of the grinding wheel slide 1 with respect to the orbiting pin 18. Machining is continued in a process in which the grinding wheel slide 1 continues to be displaced laterally with respect to the rotational axis 8 of the shaft 34. This is because the pin 18 follows the pin 18 substantially without any machining feed displacement toward the axis 2 of the pin 18 during one rotation of the pin 18. In this final step, the outer surface of the pin 18 is made substantially circular in order to obtain the profile indicated by reference numeral 18F shown in FIG.

Thus, according to the method of the present invention, for example, by the method according to the embodiment described above, the moment detected by the head 39 and the point W is the radial dimension of the pin 18 actually reached at the moment of contact with the grinding wheel 4 Verification can be performed based on the value V (i). Thus, the machining of the pin 18 can be continuously controlled, for example, until the desired nominal dimension R _F is reached. Thus, parts that have been machined with particularly high accuracy and reliability can be obtained in a very short time without having to interrupt the machining feed of the grinding wheel 4.

  In the method described above, the machining feed of the grinding wheel slide 1 is relatively high speed (for example, 15 μm / s), the rotation of the shaft is relatively low speed (for example, 20 to 60 rpm), and the sampling period is 0. It can be applied to machining that is assumed to be 5 ms to 4 ms. The number N of samples per pin rotation may be in units of 1000, but the number C of average values M (j) for calculating the index P may be, for example, about 10.

A typical value of the angle α is, for example, 120 °. It should be understood that in applications such as those shown in FIGS. 1 and 2, the magnitude of angle α varies slightly depending on the geometric and kinematic characteristics of the system during component rotation. is there. However, upon inspection of the radial dimension of the pin 18, these changes that remain in the +/− 5 ° range are completely negligible. In fact, according to Equation 5, the accuracy is 5 ° decreases, a change occurs in 1.3% (5/360) the average value M (j) is a constant, substantially affect the calculation of the value _{R I} do not do.

With the correction factor K calculated by equation 5, excellent results can be obtained by applying the method according to the invention. Furthermore, a slight offset with respect to point G of the detected N instantaneous values V (i), which is the basis for the calculation of the mean value M (j), is allowed by the following equation for calculating the correction factor: can do.

  However, in most cases, when N is several tens or more (as described above, a typical value is about 1000), the difference between K and K ′ is actually It cannot be detected.

Other possible variations on the method described hereinabove assume, inter alia, different calculations of the change index. Such a calculation is for example by evaluating the angle or ratio between the detected quantity and the calculated quantity instead of the negative number P mentioned in the example above. As a result, the calculation of the instantaneous radial dimension R _I, Formula 4 is changed.

  In another embodiment, the change index P is obtained not by calculation, but by, for example, an operator directly setting a predetermined value based on the machining feed rate. In fact, if the machining feed rate is constant, the index P is also constant, and there is no need to dynamically calculate the change index P at each part rotation. In other words, when the machining feed rate is constant, the slope of the curve M is constant, the change index P can be provided to the arithmetic processing-display unit 22, and no further arithmetic processing is performed.

This embodiment is particularly advantageous when the part is subjected to two or more machining steps at different machining feed rates. By setting the value of the change index P for each machining process, when transitioning from one machining process to the other machining process and thus from one machining feed rate to the other machining feed rate it is possible to improve the accuracy in the dynamic calculation of the instantaneous radial dimension R _I when.

  In another embodiment, the change index P can be dynamically calculated based on a preset number of initial values M (j). The calculated change index P is then used in subsequent processing, in exactly the same manner as described hereinabove. In order to minimize errors in calculating the change index P, an average value of the calculated values of a predetermined number of change indices P can be evaluated.

  For certain applications where the nature of the machined part's shape error is substantially known in advance, the average value M (j) can be moved with a predetermined magnitude that can be programmed (eg, 120 ° or 180 ° wide). Rather than being based on a free angle range, the evaluation can be based on a predetermined number of instantaneous values V (i) smaller than N.

  Obviously, the method according to the invention can be applied to other instantaneous values V (i) detected by the head 39 signal in order to compensate for changes due to, for example, thermal changes or head 39 linearity limitations. It can also be used to add arithmetic processing.

  The method and apparatus according to the invention are advantageously applied to inspecting orbiting pins with a head having a V-shaped reference device, as explained above. Similar methods and apparatus can be applied to control the machining of the main journal 38 of the shaft 34 described with reference to FIG.

  In addition, for example, a control method and apparatus using a head with two contacts to provide a signal indicating the diameter dimension of the part rotating about the axis of the part itself, or a contactless inspection head (optical or other type) ) Are included in the scope of the present invention and are controlled in many applications with the same standard of accuracy, reliability and speed of machining in machine tools such as grinding machines. it can.

As described above, the method and apparatus according to the invention, a value indicating the actual size of the region in contact with part of the tool to be machined (as R _I), can be obtained for each moment. The use of such a value (R _I ) to control one or more machining processes is generally determined and managed by the machine controller (eg numerical controller 33). The

FIG. 1 is a side view of a measuring device attached to a grinding wheel slide of a crankshaft grinder in a machining state during inspection of a crankpin. FIG. 2 is a schematic enlarged detail view of FIG. FIG. 3 is a block diagram of a preferred embodiment of the control method according to the present invention. FIG. 4 is a graph showing several quantity trends detected and calculated according to the method of FIG.

Claims (18)

A method for controlling machining of rotating parts (18, 38) in a machine tool by means of an inspection device,
Detecting an instantaneous value (V (i)) indicative of a radial dimension of the component (18, 38);
A step (57, 59, 60) of calculating the detected instantaneous value (V (i));
Controlling (62, 63) at least one machining step based on the detected and computed instantaneous value,
The step of calculating the instantaneous value (V (i))
Dynamically calculating an average value (M (j)) of the instantaneous values (V (i)) during the machining;
Obtaining a change index (P) indicating a tendency of the average value (M (j)) during the machining;
Dynamically calculating the instantaneous dimension (R _I ) based on the calculated average value (M (j)), the change index (P), and at least one correction factor (K); Including,
The method wherein the at least one machining step is controlled (62) based on an instantaneous dimension (R _I ) obtained by calculation. The method of claim 1, wherein
Each of the average values (M (j)) is dynamic based on a series of instantaneous values (V (i)) detected as the part (18, 38) makes a complete revolution during machining. Calculated in the way. The method according to claim 1 or 2,
In order to control the machining in a grinding machine having a grinding wheel (4) in contact with the rotating part (18, 38) in the machining area (W), the inspection device controls the part (18, 38). ) And at least one inspection area (G), the correction factor (K) is evaluated based on the arrangement of the machining area (W) and the at least one inspection area (G). The way. The method of claim 3, wherein
The method wherein the instantaneous dimension (R _I ) is an evaluation of the dimension of the part (18, 38) in the machining area (W). The method according to claim 3 or 4,
The inspection apparatus includes an inspection head (39) having at least one contact (17) in contact with the component (18, 38) in the at least one inspection region (G), and the correction coefficient (K) is The method is evaluated on the basis of a geometric feature (α) of the arrangement of the grinding wheel (4) and the at least one contact (17) with respect to the parts (18, 38). The method of claim 5, wherein
The inspection head (39) includes a V-shaped reference device (20), and the at least one contact (17) is along a direction substantially coincident with the V-shaped bisector, or the bisector. Wherein the instantaneous dimension (R _I ) obtained by the calculation is a radial dimension. The method according to any one of claims 1 to 6,
The change index (P) is obtained by calculation. The method of claim 7, wherein
The change index (P) is calculated based on the newest average value (M (j)) obtained by dynamic calculation. The method of claim 8, wherein
A method in which the average value (M (j)) on which the change index (P) is calculated has a predetermined number (C). The method of claim 9, wherein
The change index (P) is expressed by the following formula:

Calculated by the method. A method according to any one of claims 1 to 10,
In order to control the machining until the nominal dimension (R _F ) of the part (18, 38) is reached, the machining of the part (18, 38) is determined by the instantaneous dimension (R _I ) And the nominal dimension (R _F ). In an apparatus for inspecting rotating parts (18, 38) during machining on a machine tool with a numerical control device (33),
An inspection head (39) adapted to cooperate with the rotating part (18, 38) and to transmit an electrical signal indicative of the dimensions of the part (18, 38);
An arithmetic processing-display device (22) connected to the inspection head (39) and the numerical control device (33) of the machine tool, receives the signal from the inspection head (39), and receives an instantaneous value (V An arithmetic processing-display device (22) adapted to detect and compute (i)) and provide a signal indicating the dimensions of the components (18, 38) to the numerical control device (33); The processing-display device (22) includes the following dynamic calculations:
Calculation of the average value (M (j)) of the instantaneous value (V (i)), the average value (M (j)) obtained by the calculation, and the average value (M (j)) during machining Calculating an instantaneous dimension (R _I ) of the part (18, 38) based on one of a change index (P) indicative of a change of at least one and at least one correction factor (K). And
The processing-display device (22) is adapted to provide the numerical control device (33) with the instantaneous dimensions (R _I ) of the components (18, 38). The apparatus of claim 12, wherein
In order to control machining in a grinding machine with a grinding wheel slide (1) supporting a grinding wheel (4) in contact with the parts (18, 38) in a machining area (W), the inspection head ( 39) cooperates with the parts (18, 38) in at least one inspection area (G), and the arithmetic processing-display device (22) includes the machining area (W) and the at least one inspection area. The correction coefficient (K) is calculated based on the mutual arrangement with (G). The apparatus of claim 13.
The inspection head (39) includes a contact (17) and a V-shaped reference device (20) adapted to contact the parts (18, 38) to be inspected, the at least one contact ( 17) The device is movable with respect to the V-shaped reference device (20). The apparatus of claim 14.
In order to inspect the pin (18) that is orbiting about the axis of rotation (8), the V-shaped reference device (20) contacts the pin (18) substantially by gravity. The device that is supposed to maintain. The apparatus of claim 15, wherein
The inspection head (39) is movably supported, and the contact (17) and the V-shaped reference device (20) can be maintained in contact with the pin during the orbital motion of the pin (18). Comprising a support structure (5, 6, 9, 10, 12). The apparatus of claim 16.
The support structure (5, 6, 9, 10, 12) is connected to the grinding wheel slide (1) of the grinding machine and includes a connecting element (9, 12) that rotates in a reciprocating manner. Including the device. The device according to any one of claims 12 to 17,
The said arithmetic processing-display apparatus (22) is an apparatus which performs the dynamic calculation of the said change index (P) based on the newest average value (M (j)) calculated dynamically.

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